Will Herobrine Ever Be Added to Minecraft Xbox 360 Edition?

No. Herobrine is a community creepypasta (2010), never in the game code. Mojang has confirmed this repeatedly (changelog: "Removed Herobrine" × many versions as a joke).

Why It Won't Happen

• 4J Studios (Xbox 360 Edition dev) only ported features from official Java/Bedrock codebases. Herobrine was never in either.
• Legacy Console Editions are frozen. Last update: TU73 (2018). No new content ever.
• Legal/IP: Herobrine is a fan creation; adding it implies endorsement of a myth Mojang denies.

If You Want Herobrine

• Java Edition + Mods: "Herobrine Mod" (Forge/Fabric), custom maps (Herobrine's Mansion), resource packs.
• Bedrock Add-ons: Behavior/resource packs on MCPEDL.
• Console (Xbox One/Series/Switch/PS4/PS5): Bedrock edition supports marketplace add-ons (some Herobrine-themed).

The 360 Edition will never see Herobrine. Play on a platform that supports mods/add-ons.